1. Technical Field
The invention relates to the field of electronic devices having microchannel plates (“MCPs”), and more particularly to methods of bonding a microchannel plate (“MCP”) to other components.
2. Background Art
The present invention describes methods of bonding electro-optical components to a feed-through. The methods described herein may include bonding of other electrical, optical and mechanical components where:
a. mechanical hold downs or retainers are not desired;
b. morphology of the two bonding materials is not adequate for a direct surface to surface bond;
c. bonding involves brittle materials with low shear strength;
d. a bonding process that does not require solders or braise joints;
e. a bonding process that does not require melting of the bonding material;
f. mechanical and electrical bonds are desired on the same interface;
g. the bonding must provide both electrical and mechanical interconnects; or,
h. creation of the bond does not permanently alter the components being bonded.
Prior Methods
Method 1: Kovar rings brazed to ceramics to facilitate compressing the micro-channel plate (“MCP”). This method requires contacting both sides of the micro-channel plate to facilitate both the electrical and mechanical interconnects, and this is the primary disadvantage compared to this invention. The upper ring would serve as the upper electro-mechanical inter-connect, and the lower ring would serve as the lower electro-mechanical interconnect. This method has been used for decades to manufacture image intensifier devices.
Method 2: An alternative method is described in U.S. Pat. No. 6,040,657 that uses solder or brazing materials of Indium, Indium tin Alloys, Gold—Tin alloys and Gold—Germanium alloys, etc. to flow and wet the micro-channel plate to the feed-through assembly. A primary disadvantage to Method 1 is that a large perimeter portion of the micro-channel plate is covered by a retainer ring used to hold the micro-channel plate in position. The retainer ring occupies space in the ceramic feed-through and also requires complimentary rings to hold and position the retainer; in all there are at least 4 additional rings in the feed-through required for this Method. Additionally the perimeter coverage of the micro-channel plate restricts the design of the cathode input window, because it must accommodate the added height of the retainer and complimentary supports.
Added costs are incurred by Method 1 due to the additional supports and inherent yield losses due to assembly.
A primary disadvantage to Method 2 is that the micro-channel plate must be coated with a metal electrode suitable for bonding with the alloy material. Patterning the electrode to provide electrical and mechanical interconnects to the micro-channel plate becomes very difficult because the flow of the molten alloy material is uncontrolled. The uncontrolled flow of the alloy may allow contact with the micro-channels, which is undesirable for proper operation. The primary advantage of the current invention is that there is no flow of material.
Method 2 eliminates only 1 of the support rings so there are still 3 additional pieces required over the present invention.
U.S. Pat. Nos. 5,514,928 and 5,632,436 disclose “interbonding” two or more micro-channel plates using an alloy similar to those described in Method 2 above. These patents do not discuss bonding of a micro-channel plate to a ceramic feed-through.
U.S. Pat. No. 6,040,657 teaches a “solder pin” to conductively contact the micro-channel plate as described in Method 2 above.
U.S. Pat. No. 5,994,824 discloses a “metallized snap ring” similar to that used in Method 1 above.
U.S. Pat. No. 5,573,173 teaches “diffusion bonding,” but describes use with an electron gun and a cathode ray tube.
While the above cited references introduce and disclose a number of noteworthy advances and technological improvements within the art, none completely fulfills the specific objectives achieved by this invention.